This invention relates to multiconductor cables used for transmitting electrical signals, and particularly to the attachment, during manufacture of the cables, of connectors at the ends of the cable for providing electrical connections to the cable conductors.
While the present invention has utility with various types of signal transmitting cables, it has particular use with cables comprising twisted pairs of wires used in the telecommunication industry. By "twisted pairs" it is meant that the two wires of each pair are wound around one another in a pair of intertwined spirals; the twisting together of the two wires being effective for noise suppression. Each pair of wires provides a separate communication channel and, for signal routing purposes, all the wires within the cable terminate at preselected ("dedicated") contacts (e.g., prongs of plug-type connectors) of the two end connectors. Thus, within each connector, all the wire pairs are in preselected sequence and, for each wire pair, the two wires (typically referred to in the telecommunications industry as "tip" and "ring" wires) are likewise in preselected orientation (the tip wire always being, for example, to the left of the ring wire with a given orientation of the connectors).
In the manufacture of such telecommunication cables, continuous cables are made, cut to desired lengths, and connectors are attached to each cable end. The latter process comprises removing the cable sheathing at the cable ends, identifying and sorting the wire pairs into a preselected pattern, untwisting end lengths of wires from each wire pair, and disposing the two wires of each pair in proper side-by-side relation. When the cables are of the "flat" ribbon type, comprising side-by-side pairs of wires in fixed relationship over the lengths of the cables, no sorting of the wire pairs is necessary. However, owing to the twisting of the wires of each pair around one another, it is not possible to know in advance, upon the cutting of the cables, the relative side-by-side positions of the wires of each pair. Thus, in all instances, it is necessary to selectively untwist the wires of each wire pair more or less as is necessary to dispose the two wires in proper side-by-side relationship.
The wires are color encoded, e.g., the ring wire is always of a darker color then the tip wire, and a human operator has little difficulty in identifying the wires of each wire pair and properly positioning them. It is desired, however, to automate the connector assembling process and a quite serious problem encountered is that of designing a machine to perform the wire pair selective untwisting and side-by-side sorting process. Indeed, while various aspects of cable manufacture are substantially completely automated, successful automation of the process of side-by-side sorting of the wires of each pair has not been achieved. Such process is greatly simplified in accordance with this invention.